DIY Wall Insulation shows many things you can do yourself to make your walls more air-tight and better insulated if you are handy. The topics “Types of Siding Available” and “Insulated Siding” will help prepare you to hire a siding contractor and choose the materials which will best increase the insulation of your walls.


The Pros and Cons of Making Your Walls Air-Tight
How to Caulk Exterior Walls
Check for Missing Insulation in Your Walls
Blower Door Tests and Thermal Imaging Scans
DIY Ways to Add Wall Insulation
How to Seal Gaps Above Foundation Walls
DIY Basement Wall Insulation
How to Fill Empty Walls with Loose Fill Cellulose Insulation
How Do You Insulate Walls by Doing Repairs to Seal Air Leaks?
Types of Siding Available
Insulated Siding

The Pros and Cons of Making Your Walls Air-Tight

Before sealing the leaks in your walls, consider the possible problems with having less air entering your home. Sealing the leaks could make the air quality worse, which could  present problems for some persons.

If you fry foods often and you don’t have an exhaust fan above your stove, or if there are smokers in your home, sealing the leaks could make the air uncomfortable for some.  If you use a fireplace, making your home more air-tight could cause the fire to burn poorly. You could solve this problem by cutting a hole in the floor on each side of the fireplace and covering them with heating register grilles, which you open when using the fireplace.

In addition to lowering your utility bills, there are may other advantages to sealing the gaps and small holes your walls. Gaps and small holes may allow rain water to enter and damage the walls, they can allow mold to grow in the walls, making allergy symptoms worse, and they can allow insects to enter. Caulking large gaps could reduce a feeling of draftiness on very cold days. In some homes, doing only the DIY project of sealing gaps and small holes will result in a major improvement in the wall insulation.

How to Caulk Exterior Walls

All materials expand and contract with changing temperature and humidity, so cracks can form wherever two large surfaces meet, especially if they meet at an angle or if they are of different materials. Cracks can also form where nails have come loose and where wood has dried out and contracted. Inspect the lines where large surfaces meet, and if possible, on a bright, sunny day.

Where to Apply Caulking Outside Your Home

how do you insulate walls


    • Caulk wherever large surfaces of unlike materials meet and where two large surfaces meet at an angle. If you have aluminum, vinyl or steel siding, do not caulk the gaps at the inner or outer corners of the house if it would prevent the siding from expanding in hot weather. Caulking it could cause the siding to buckle.
    • Under the window sills and door thresholds.

      how do you insulate walls

      caulking around a window frame

    • Around door and window frames. If the walls have aluminum, vinyl or steel siding, and the climate is hot, it is often better to leave a gap, to allow the siding to expand without buckling.
    • Around wall lamps and receptacles. This will seal air leaks and also prevent moisture from causing rust damage. If a receptacle is embedded in the wall, remove the cover plate and caulk between the box and the wall. If the cover plate screw is rusty do not remove it because its head could break off.
    • Fill gaps around gas pipes, water pipes, electric cables and air conditioning tubes. If a gap is wider than about ¼”, use expanding foam sealant in place of caulk.
    • Around phone lines and cables.
    • Around drier vents, bathroom exhaust vents and kitchen exhaust fans. Use clear caulk if the walls are masonry.
    • Between the storm door frame and the house using clear caulk.
    • Do not caulk below the bottom edge of wood siding, between the foundation and the siding because if water leaks in behind the siding it needs a path to escape.
    • If a large pipe that was once used for heating oil enters the house through the basement wall and it is not capped, cap it or fill it with expanding foam sealant.
    • If your house has an overhang, i.e. one floor extends beyond the floor below it, caulk along the bottom of the overhang. First, check if the wood panel beneath the overhang is firmly mounted and secure it with screws if it isn’t.
    • If you have a brick chimney next to wood siding, caulk the corners where they meet, using clear caulk. Water entering here would cause the siding to rot.
    • If your walls are brick, stone, block or stucco, check for cracks. Repair small cracks with masonry caulk. This is better than mortar because mortar cannot be forced into thin cracks. Also, mortar would be smeared on the wall and is hard to clean off. Very small cracks should be repaired because water could enter them and freeze, harming the walls. See How Do You Insulate Walls by Doing Repairs to Seal Leaks.
    • If you have a crawl space next to a basement, check the wall between them from the crawlspace side. Some holes and gaps may only be seen from that side. The holes should be filled even if the basement is unheated because much cold air will be drawn in though them in the heating season.
    • If the dryer vent passes through a rigid plastic window pane with a hole cut through it, check if the dryer hood has come loose from the pane. Attach it with polyurethane construction adhesive, and tape it to the pane with duct tape until the adhesive dries. If the hood is well-attached, check if there is a gap.

Where to Apply Caulking Inside Your Home

    • If your basement is unfinished and your foundation walls are exposed, caulk the holes where phone lines, cables and piping enter the house. If the holes are large use expanding foam sealant.
    • Caulk any gaps at the tops and bottoms of the baseboards on the exterior walls.
    • Check for gaps where the window and door frames (casings) meet the walls. Sealing these gaps could also prevent water vapor from entering the walls, possibly allowing mold to grow. Check the frames around the basement windows and doors also. If your basement walls are bare block or concrete, gaps could be large. Fill gaps that are less than about ¼” wide with exterior caulk because the wall may get damp. Fill wider gaps with “expanding foam sealant for windows and doors”. This expands less than other types of expanding foam sealant, preventing the frame from bending. When the central heating is on, air is drawn in forcefully through gaps in the basement door and basement window frames due to the “chimney effect”.
    • Check for a gap where the dryer vent passes through the wall. If the wall is brick or block, there may be large gaps around the vent, and they should be filled with any type of expanding foam sealant. Fill small gaps with exterior caulk. If there are large gaps filled with fiberglass insulation, replace it with expanding foam sealant because  fiberglass insulation doesn’t stop air leakage.
    • Caulk gaps around the fireplaces. Use siliconized acrylic caulk in the color of your wall if it is available, or use clear.
    • Check for gaps where a stairway runs along an exterior wall. The baseboard is normally notched to fit over the steps, and there may be gaps between the steps and baseboard.
    • If your utility meters and electric panel and water shut off valves are in the basement wall with access doors, check for air leaks around these doors. Move an incense stick or candle around the edges of the doors, or tape a thin plastic sheet over each door and check if it billows in or out. If air leaks through, seal around the door or panel with thin, compressible, self-adhesive foam weatherstrip tape.

      how to insulate walls

      Fireplace damper

    • If you have a fireplace that was covered over by drywall, check if air is entering your house through it by checking if the wall feels cold there on a cold day. If so, air is probably leaking around the damper. In very old homes, the dampers were not designed to be air tight. Cold air in the chimney is falling down into your wall. Cut a large, square hole through the drywall to reach through to the damper.  Cut it carefully so that the piece you remove can be used to repair the hole. If cold air is leaking past the damper, use spray foam insulation to fill gaps around it.
    • If your basement walls are exposed foundation block, check for air leaking through the foundation. Foundation blocks are hollow, and air can flow up and down inside a wall. If there is a spot where mortar is missing on the inside surface of the wall, air may enter the wall at a different place and flow to that spot and enter the house.  You could check for air leaks by moving an incense stick all over the walls or by looking for missing mortar. The smoke from an incense stick can detect much smaller air leaks than a candle. Some leaks are only detectable when the wind blows. Fill any holes in the walls with masonry caulk or mortar.

How to Apply Caulking 

In this section, the term “caulking” refers to both caulk and sealant. They are applied in the same way. The products designed for indoor and indoor and outdoor use are normally caulk, and the products designed for outdoor use are normally sealants.

    • When applying caulking from outside of the house, work on a day that meets the conditions given on the tube of caulking. It is best to work on a sunny day so you can see cracks. Don’t apply it before 10:00 AM because the surfaces could be wet from dew.
    • If the caulking is cracked, it is very old and has dried out, try to remove and replace it all. Scrape it out with a sharp ½” wood chisel.
    • Prepare the surfaces that appear dirty. Metal, glass, wood and plastic can be cleaned with mineral spirits or rubbing alcohol. Concrete, brick, block and stone can be cleaned with a wire brush. Remove debris from gaps with a paint brush.

      energy tips for walls

      5/8″ and 1/4″ backer rods

    • Fill gaps that are deeper than the maximum depth given in the directions (3/8” or ½”) with foam backer rod to reduce the gap before applying the caulking. Backer rods called “poly foam caulk savers” are 5/8” diameter and are sold in the weatherization departments of home centers and hardware stores. Many painting stores sell ¼” foam backer rods.
    • Fill wide, deep cavities in the wall inside the house with expanding foam sealant. This is costly to use for a single cavity in the wall because it dries up in the can a few hours after it is used.
    • If siding is loose at an end where you are applying caulk, fasten it using spiraled siding nails. If the siding is asbestos or fiber cement (these are shingles designed to appear like asbestos shingles), pre-drill the nail holes with an 1/8” masonry bit to prevent cracking. If nailing it doesn’t attach it firmly, the sheathing behind it is probably slightly rotted. Try nailing in two siding nails, one at a small angle to the left and one at a small angle to the right (toe nailed). If nailing it cannot attach it firmly, remove a large section of siding and replace the sheathing in that area. To remove the siding without damaging it, see Replace Damaged Boards of Lap Siding.
    • If you are using acrylic caulk that is months old, soak it in warm water. One of the mistakes DIY homeowners often make is using materials, such as caulking, that is not fresh enough. If acrylic caulk was ever exposed to freezing temperatures it must be discarded. Don’t use caulk that is over one year old. If unsure how old the caulk is or if it was in freezing temperatures, test it. Apply a few inches of it to check how well it comes out of the tube. Then, wait for it to dry and check if it adheres well.

      Caulk Applied as a Wide Bead


    • When caulking outside the house, push the caulking gun forward to force the caulk into the gap, and apply the caulk slowly. Make every bead of caulk as wide as possible so it can expand more as the two surfaces move relative to each other. Press each bead down with your finger so they adhere to the surfaces well.
    • When caulking inside the house, you may  choose to pull the gun for a neater appearance. Press the bead down with your finger to make an attractive concave surface and to make the caulking adhere better. Carefully remove the excess caulk
      with a putty knife.
    • Water-based (acrylic) caulk can be cleaned off with water, and oil-based (solvent-based) caulk can be cleaned off with mineral spirits or paint thinner. On all types, this is written on the tube.

Which Caulk or Sealant Should You Use?

    • The terms “caulk” and “sealant” are often used interchangeably, but they are not the same. They are applied the same way. Sealants are more elastic-they are made from materials that expand and contract more than caulk. The products formulated for indoor use or for both indoor and outdoor use are normally caulks, and the products formulated for outdoor use only are normally sealants. Caulk is better than sealant for indoor use because it has a neat appearance.
    • There are so many types of caulk and sealant in a paint department or paint store that a DIY homeowner could be overwhelmed. Some are for special conditions, such as high temperatures, fireproofing, or wet surfaces. Some only save you money. Cord caulking only has the advantage that it is easy to apply; it is not durable enough for general use. Latex and acrylic latex caulk are not durable enough if you are sealing cracks. They may need to be re-applied each time the house is painted.
    • If you are buying a caulk only to seal air leaks inside the house, use siliconized acrylic latex caulk (also called silicone acrylic) caulk. It is relatively durable, easy to apply, and paintable. It may be available at your store in white, clear and brown, and paint stores offer it in many colors.
    • If you are caulking outside the house, use a sealant. As explained above, sealants are more elastic. Outside, the wide changes in temperature will cause a gap between different materials to expand and contract, requiring a more elastic product. Silicone sealant is very durable and very elastic, but there are others also. Carefully read the label before buying a sealant. Silicone sealant, for example, cannot be applied at low temperatures, but there are brands of sealant that are formulated for use at low temperatures. Most brands of silicone are not paintable, but some are.
    • Some of the main advantages and disadvantages of several of the more durable types of caulk are given below. The largest selection can be found at home centers, but paint stores carry the best selection of colors. Butyl rubber sealant has basically been replaced by several sealants that are sold in roofing departments, such as “rubberized elastomeric cement” and “gutter and flashing sealant”.

Caulks and Sealants for Use Outside the Home, and Expanding Foam Sealant

Siliconized Acrylic Latex Caulk (Silicone Acrylic)

    • Easy to apply
    • Fairly good durability-10 to 20 years
    • Paintable
    • Adheres to almost all surfaces. At least one brand can be used on wood, glass, aluminum, masonry, brick, and metal.
    • Available in many colors
    • Less elastic than sealants
    • Most brands must be applied at above 40º
    • Moderate cost
    • Not permanently flexible

Silicone and Silicone Rubber Sealant

    • Very durable-products range from 10-year durability to 50-year durability
    • Permanently flexible
    • Can be used in areas of high temperature, such as lighting fixtures
    • Can be used in very damp areas
    • One brand of silicone rubber caulk can be applied in very cold weather but silicone caulk cannot be
    • Sold in several colors
    • Most brands do not adhere to brick or concrete, but at least one brand is designed for metal, brick, concrete and granite
    • Cost is high

 Polyurethane Sealant

    • Very good adhesion and durability
    • Permanently flexible
    • Stretches well
    • Sold in many colors.
    • Formulated for wood, glass, metal, masonry, stone, PVC
    • Cost is high

Masonry Sealant

    • Best sealant for masonry walls
    • Normally only available in the color of concrete.
    • Paintable

Expanding Foam Sealant

    • Fills gaps that are too wide for caulk
    • Expands to fill irregularly-shaped spaces
    • Lasts 10 or more years
    • Cans have “one time use”, so often, most is wasted
    • “Double-expanding” and “triple-expanding” brands can bend wood boards, such as door jambs

Caulks and Sealants for Use Inside the Home, and Expanding Foam Sealant 

Siliconized Acrylic Latex Caulk (Silicone Acrylic)

    • Easy to apply
    • Less expensive than most types of caulk
    • Fairly good durability-10 to 20 years
    • Paintable
    • Adheres to almost all surfaces. At least one brand can be used on wood, glass, aluminum, masonry, brick, and metal.
    • Available in many colors
    • Most brands must be applied at above 40º
    • Cost is moderate

Silicone and Silicone Rubber Sealant

    • Most durable of these types of caulk
    • Stretches and compresses better than other types (more flexible)
    • Permanently flexible, crack-proof, shrink-proof
    • Can be used in areas of high temperature, such as lighting fixtures
    • Can be used in very damp areas
    • Available in several colors
    • Most brands do not adhere to brick or concrete, but at least one brand is designed for metal brick, concrete and granite
    • High cost

Expanding Foam Sealant

    • Fills gaps that are too wide for caulk
    • Expands to fill irregularly-shaped spaces
    • Lasts 10 or more years
    • Cans have “one time use”, so often, most is wasted
    • Some brands recommended for use outdoors, except in warm climates
    • Some brands should be painted to protect from UV radiation
    •  “Double-expanding” and “triple-expanding” brands can bend wood boards, such as door jambs. Around windows and doors, use “window and door insulating sealant” expanding foam sealant.

Check for Missing Insulation in Your Walls

On a very cold day, check for cold spots on the interior surfaces of your exterior walls. If your basement is “finished”, check the basement walls also. A cold spot indicates that air is leaking into the wall from the outside or that some wall insulation is missing. It could be missing near the top of a wall if it is loose fill insulation and it slid down.

    • One way to check for cold spots is to feel the walls on a very cold day. Cold spots are much more likely to be next to doors and windows and at the tops of walls. The most accurate way is with a non-contact infrared thermometer. These detect cold spots in winter and warm spots in summer. They are sold at home centers, starting at about $25. You can use it to check for missing roof insulation if your attic is finished, and check the basement walls for cold spots caused by infiltration. In some homes, only the original rooms, which were built before fiberglass batt insulation was available, have cold spots at the top, because loose fill insulation was blown into the walls and it has settled. If your home is very old, check along the bottom of the basement walls. The insulation there may be missing due to water damage or rodents.
    • Cold spots close to windows and doors may be caused by air leaking into the walls where the frames meet the wall. If you have cold spots here, check if the caulking there is cracked or missing.
    • If you find places where wall insulation is missing, you could fill the empty spaces with triple-expanding spray foam insulation. This is contained in liquid form in a pressurized can. It is sprayed into the walls through a ¼” tube, through ¼” holes drilled into the walls, and expands greatly to create hard foam. The triple-expanding type expands to the greatest volume. This is expensive so it is only be a good investment in very cold climates.

To apply spray foam insulation into the top of a wall, tap along the wall to locate the studs. They should be spaced at 16” intervals. Between every two studs, drill a ¼” hole and spray in the foam. After it has expanded, check if the cold area is completely warm or if more foam should be added. If the insulation is missing from floor to ceiling between two studs, drill a hole about a foot from the floor, spray in some insulation, let it fully expand, and then check how much area is still cold to find how many holes to make. There should be a board near the center (a fire stop). Locate it with a stud finder or by tapping the wall.

Blower Door Tests and Thermal Imaging Scans

Some companies that perform home energy audits to find the places where your home wastes energy will instead do a “blower door test” together with a “thermal imaging scan” in place of a complete home energy audit, if requested. These two tests identify places in your exterior walls where energy is being wasted. In a blower door test, a large fan (blower) placed in the front doorway, blows air out of the house. The air pressure in the house becomes lower, causing air to flow into the house more strongly through any leaks in the walls, so that small leaks can then be detected.

In a thermal imaging scan, also called an “infrared thermography inspection”, the energy auditor uses an infrared camera to take infrared pictures of your home from the inside and the outside. The pictures show different temperatures in different colors.  Where air is leaking out of the house the picture shows colors that indicate warm spots. A thermal imaging scan can also identify problems in your roof’s insulation and moisture problems which could damage your house. The picture above shows a yellow spot on the roof, where insulation is missing.

DIY Wall Insulation


After Having an Infrared Imaging Scan:

    • If a scan taken from outside shows that much heat is escaping from between the first and second floors or from between the second and third floors, it is escaping at the band joists. These are 2”x 10” beams along the perimeter of each floor. If the heat detected is minor it may be heat that is conducted through the band joists. If it is significant, air is leaking out of the house from above or below the band joists. You may be able to hire an insulation contractor to remove a piece of siding at the band joist, drill ¼ “ holes through the band joist and shoot in foam insulation to fill the space behind it. Only trained contractors can do this.
    • If a scan shows that small areas of a wall are missing insulation, you could fill the empty spaces with triple-expanding spray foam insulation. This is contained in liquid form in a pressurized can. It is sprayed into the walls through a ¼” tube, through ¼” holes drilled into the walls, and expands greatly to create hard foam. The triple-expanding type expands to the greatest volume. You can do this yourself if you can patch a small hole and match the paint, but it is expensive and may only be a good investment in very cold climates.

To apply spray foam insulation into the top of a wall, tap along the wall to find the approximate locations of the wall studs. They should be spaced at 16” intervals. Between every two studs, drill a ¼” hole and spray in the foam. If the insulation is missing from floor to ceiling between two studs, drill a hole about a foot from the floor, spray in some insulation, let it fully expand, and then check how much area is still cold to find how many more holes to make. There should be a board near the center (a fire stop). Locate it with a stud finder or by tapping the wall.

    • If a scan of your basement ceiling shows that much air is entering the ceiling through the walls, there is probably a large gap between the foundation and the board that rests on it (the sill plate). To caulk this gap, see Seal the Leaks at the Top of the Basement Wall

How to Seal Gaps Above Foundation Walls

Your home’s basement walls or crawlspace walls are its foundation walls. A sill plate, which is normally a 2”x 6” board, rests directly on the foundation walls all around the house. There are often gaps between the foundation walls and the sill plates because the top surface of the concrete or blocks is not smooth. On older homes, this gap was likely to have been caulked with oil based caulk, which may last for only 30 or 40 years, and then shrinks to allow large gaps. Also, where gaps are too wide for caulk the gaps may never have been sealed.

    • In place of a basement, your home may have an underground crawl space, or only one room may have a crawl space below it. These are about 3 ft. high and normally have bare earth at the bottom. There are normally two vents in the walls of each crawl space to allow air to flow in and out, to allow water vapor to escape. Do not caulk above these foundation walls because the moist air should escape.

      Pneumatic Stapler


    • If the top of a foundation wall is not in sight and you have a suspended ceiling (drop ceiling), remove a row of ceiling panels. If you have ceiling tiles, you could cut out a row of them, but when remounted, their appearance will not be perfect. To remount them you must use 1” staples, which requires a pneumatic stapler or other type of power stapler.
    • If you have a finished room in your basement that was originally a garage, it is likely that caulking was not applied at the top of the foundation wall, so it should be checked.
    • If your basement ceiling is drywall, it may be worth your effort to cut away a 16” strip of the ceiling along walls where there are cold spots on the ceiling, to access the foundation wall. One way to check the ceiling for cold air is to cut a few 5”x5” holes and reach in to check for cold air. A 5”x5” hole can be patched with a 6”x6” wall patch, but to repair these holes requires experience in plastering. You could hire a painter for this. Instead of making holes, you could check for large leaks by checking if the ceiling near the wall feels cold on a very cold day. Another way to check is to use a non-contact infrared thermometer. These detect cold spots in winter and warm spots in summer. They are sold at home centers, starting at about $25. To remove a strip of drywall:

      Spiral Saw


    1. Snap a chalk line across the wall to mark the cutting line.
    2. Use a sharp utility knife with the blade extended exactly ½”, the thickness of the drywall. DO NOT USE A WALLBOARD SAW because you could cut a power cable, phone line or other cable. Cables often lay on top of the ceiling. A faster and equally safe  way to cut a drywall ceiling is use an electric tool designed to cut drywall, such as a “spiral saw”. Set the cutting bit to the thickness of the drywall, 1/2”.
    3. Apply sealant to the top and bottom surfaces of the band joists (rim joists). They are wooden beams that rest on edge on the sill plate along every wall. If there is fiberglass insulation against the band joists, remove it to caulk, fiberglass insulation does not stop air from leaking in.
    4. If your climate is very cold, staple insulation against the band joists before closing up the ceiling. This is commonly done in cold climates to increase the R-value of the band joists. Do not use insulation that could trap moisture, such as rigid foam, because moisture could cause the band joists to become damp, and possibly rot. Use un-faced, 3½” thick fiberglass batt insulation. If only faced insulation is available, tear off the paper facing. On the walls parallel to the floor joists, the joists may be double so insulation should not be needed.
    5. Replace the 16″ strip of drywall and plaster the seam. This must be done by someone experienced in plastering.

DIY Ways to Add Wall Insulation
A wall’s R-value is its ability to resist heat flowing through it, due to reflection of heat radiation and also conduction through it. The R-value does not indicate how much energy is lost due to air leaking through the wall. R-values are given in ft2-deg-hr/Btu. It could be explained as the Btu’s that would pass through one square foot per hour, for each degree in temperature difference between the inside and outside of the wall.

“Dead air insulation” is any thin space between materials in which air is trapped. It insulates better than a thick space of trapped air because in a thick space (approximately 1″ or greater), air moves from the hotter side to the cooler side in a convection cycle. A thin space of trapped air (dead air) insulates well because it blocks conduction of heat and because the surfaces on either side of it each resist heat radiation. Double-glazed windows, for example, insulate well due to the thin space between two panes of glass.

Do not insulate the crawl space walls. There is normally one vent on each crawl space wall to allow air to flow in and out, so the air temperature in the crawl space will be close to the outdoor air temperature regardless of the insulation in the walls. Also, the vents should be left open to prevent the water vapor that rises from the ground from damaging the floor joists. Instead of insulating the crawlspace walls, insulate the surface at the top of the crawl space with fiberglass batt insulation.

Brick Veneer Walls

    • All modern brick homes have brick veneer walls. These have one layer of brick covering a framed wall. If your walls are brick veneer, do not fill  the gap behind the bricks with insulation because this drains away water. Water enters the gap as it condenses after contacting cold bricks, and as moisture entering through the bricks. Water trapped in the wall would damage the framing.
    • If your air conditioning costs are much higher than your heating costs, you could paint your walls white to reflect the heat.

Solid Masonry Walls

    • If you have brick, block or stone walls and your home was built over a hundred years ago, your walls may be solid masonry instead of having  wooden framing.  To check, remove a switch plate cover and look in using a flashlight. If the wall is solid masonry, its interior surface may be plaster applied directly to the brick, block or stone, or there may be a layer of plaster with a space behind it.

If there is space behind the plaster and the top of the walls are accessible from the attic, you can pour in vermiculate or perlite insulation balls, filling the space. If you have block walls you can pour the balls into the walls through the holes in the blocks. If your home is two or three stories, you can only insulate the top story with insulation balls for any of these types of walls.

Vermiculite has an R-value of about 2.1-R per inch of thickness and perlite is about 2.7-R (3½” fiberglass insulation is about R-3.3). However, they won’t increase the R-value of the wall by this much because the space they would fill is “dead air insulation”. See Dead Air Insulation Thus, it may not be cost effective to hire a contractor to do this work. Vermiculate and perlite insulation balls are not sold at most builder supplies stores or home centers, but are sold at stores specializing in insulation materials.

    • If your walls are brick with no frame, there may be a gap between two walls of brick. This insulates the home and prevents moisture from seeping through the walls during a rain and damaging the plaster . The gap can be filled with liquid foam insulation by an insulation contractor by drilling holes between the bricks of the outer wall and shooting in insulation. The holes are only in the mortar so they can be patched with mortar and not be unattractive. This could only be cost-effective if you live in a very cold climate. It is hard to estimate the increase in R-value because the gap that would be filled is dead air insulation.
    • If your walls are solid masonry and your climate is very cold, you could install siding with insulation sheathing behind it. Your energy savings would not be enough to justify the cost, but if your walls are unattractive, it could increase the property value of your home by improving its appearance.

The most attractive types of siding may be wood lap siding, such as clapboard and shiplap, and fiber cement siding designed to appear identical to these types of siding, and vinyl siding that is designed to appear identical to these types of siding. The property value of your home would increase more by installing fiber cement siding than wood siding because wood siding requires painting and other maintenance. See Types of Siding Available and Insulated Siding Some communities have guidelines and by-laws limiting the materials that can be used.

Frame Walls with No Insulation

    • To check if you have frame walls, use a stud finder and check that it indicates  studs, normally spaced at 16”, or knock on the wall to check for solid spots every 16”. To check if they have insulation, touch the walls on a cold day. If they feel cold they are not insulated. To be certain, remove a switch plate cover and look in the wall using a flashlight.

      DIY Wall Insulation


    • If you have un-insulated frame which you will not insulate, check if air leaks through at the switches and electrical outlets. To seal leaks, put foam wall plate gaskets behind the switch plate covers and electrical outlet covers on the exterior walls. These are sold in the weatherization section of hardware stores and home centers.
    • If you have frame walls with no insulation, in most homes the best insulation to fill them with is loose fill cellulose insulation, but it may not be suitable in very cold climates. This is explained below. Loose fill cellulose insulation is shredded paper, treated with fire retardant. Blowing it in can be a do-it-yourself project, but the other insulation materials must be installed by contractors.  The only part of the project that some homeowners could not do is repairing the 3” diameter holes in the wall that they would cut to blow in the insulation, but you could hire a painter for this. You can rent a cellulose insulation blower from a home center or rental store and buy the insulation at a home center.

• Frame walls with wood siding and no insulation behind the siding (insulation sheathing) and no insulation in the walls typically have an R-value of about R-5 or R-6. If filled with loose fill cellulose insulation they are typically about R-11 or R-12, which is similar to walls with fiberglass batt insulation, which is in almost all homes built for many decades.

• To put in loose fill cellulose insulation, cut one or two 3” diameter holes every 16” horizontally, stick the tube into each hole and blow in the cellulose. The tube will be at least 50 ft. long, so you can leave the blower outside the house and run the tube to each wall through a window. See the topic How to Fill Empty Walls with Loose Fill Cellulose Insulation. These are not sufficient unstructions, you should watch a DIY video on insulating your walls with loose fill cellulose insulation.

• Loose fill cellulose insulation has several problems. In very cold climates, filling the walls with any type of loose fill insulation could cause the walls to become damp inside from condensation because warm air escaping through the inner walls condenses when it contacts cold outer walls. This is because there is no way to insert a vapor barrier into the walls, as is done when walls are built.

• This problem is less serious if the sheathing is covered with a brand of house wrap that allows vapor to pass through it, such as TyvekTM. The problem is also less serious if there is rigid foam insulation sheathing behind siding because less air passes through the walls.

• Also, if you paint the inside walls with vapor barrier paint, this will reduce the vapor passing into the walls. Some paint stores carry vapor barrier paint and at some you can order it. It is probably available only in white, but you can paint over it to change the color.

• Another problem with loose fill cellulose insulation is that some of the fire retardants used have been known to lose their effectiveness over time.

    • Walls can also be insulated by hiring a contractor to spray in foam insulation. This is recommended in very cold climates because air cannot pass through it and condense to leave vapor in the walls. The contractor drills one or two small holes every 16” and sprays in the insulation in liquid form. It is expensive, due to the labor charge and because spray foam is expensive, but it will give your walls a higher R-value than cellulose and prevent dampness from condensation. It is probably only a good investment if you live in a very cold climate.
    • Walls can be insulated by do-it-yourselfers with mineral wool loose fill insulation. This is made from rock or slag, and is used because it is more fire-resistant than cellulose, which is made from paper treated with fire retardant. It is much less popular than loose fill cellulose, and is not widely available. It is more expensive than cellulose and has a lower R-value.
    • Hiring a contractor to install any type of insulation in the walls would probably take decades to pay for itself in energy savings, but it could significantly increase the market value of your home. Insulating your walls may make your home a little quieter, but the difference may not be noticeable if you have single pane windows and no storm windows. It also provides fire-proofing because it reduces airflow during a fire.

Check with your insurance agent as to whether adding insulation would reduce your fire insurance premiums. Before buying insulation or hiring an insulation contractor, check with your local building authorities about the possibility of qualifying for a government grant or tax credit to help pay for insulation.

    • In 2004, the Oak Ridge National Laboratory published the “Whole Wall R-Value Calculator”, to estimate the R-values of walls. Using this, R-values were calculated for wood frame walls made of 2×4 studs, with wood siding. The R-values were calculated with and without rigid foam insulation sheathing behind the wood siding, with loose fill and with sprayed-in polyurethane insulation. These are only rough estimates because there are many other factors that affect the R-value of a wall, so these R-values should not be used to estimate how many years it would take you to recover your investment in adding insulation to your walls. In fact, there is probably no accurate way to estimate this. As mentioned above, if your walls have no insulation, their R-value is probably about R-5 or R-6. The Whole Wall R-Value Calculator is given below:
Type of InsulationInsulation SheathingR-Value
Loose-fill1" thickR-16
Sprayed-in polyurethanenoneR-17
Sprayed-in polyurethane1" thickR-21

Unfinished Basement Walls

“Unfinished” basement walls have bare concrete or foundation blocks as their inside surfaces. The concrete or blocks are the foundation wall, and heat passes through them with relatively little resistance. The R-value of a foundation block wall is only about R-1.5, which is not much greater than that of a single pane of glass. There are several ways to add insulation to the inside surface of basement walls. They are shown in DIY Basement Wall Insulation An experienced do-it-yourselfer could do any of these methods, but must also watch DIY videos. Each of these methods reduces the moisture that enters through the walls from the ground into the basement. This reduces the humidity throughout the house and this could slightly reduce the home’s need for air conditioning.

If you use an insulation method that includes covering the wall with drywall or paneling, and you are an experienced do-it-yourselfer, you could build a suspended ceiling or tile ceiling with the help of DIY videos to create a valuable finished basement. If you do this you should hire an electrician to install wiring.

In very cold climates, the frost line may be below the level of the basement floor. That is, the ground freezes to below the bottom of your home. In these climates, the basement walls should not be insulated because it could cause structural damage to the home’s foundation due to “frost heave”. If the frost line is below the level of the basement floor, as the ground freezes and thaws, moving up and down, it slides against the foundation. This could damage the foundation. If the basement walls are not insulated, the earth next to the foundation absorbs heat from the house so it doesn’t freeze, so frost heave is very unlikely to occur. If you are unsure of whether the frost line is below your basement floor, contact your local HUD /FHA field office. Also, check your local building codes for approved insulation procedures

Paneled Basement Walls

To insulate paneled basement walls without destroying the paneling:

  1. Thin wood paneling can be removed without damage if it was nailed on with no adhesive. To check if adhesive was used in addition to the nails, hammer the nails through the paneling at several spots using a nail set. The panels will come off there if no adhesive was used. However, adhesive may have been used in other places, so don’t start the project of removing all of the panels unless you can buy panels of matching color if necessary, to replace broken panels.

    4 ft. by 25 ft. Roll of Double Reflective Insulation


  2. If you have thick wood paneling, it will be nailed on with finishing nails, with little or no adhesive. Use a nail set to hammer the nail heads through the panels until the panels are free.
  3. After removing the paneling, mount double reflective insulation or rigid foam insulation. The paneling may be nailed to ¾” thick furring strips, which are too thin to use rigid foam insulation. If it is nailed to 2”x 3” or 2”x 4” boards you can use either rigid foam insulation or sheets of double reflective insulation. Double reflective insulation is sold at home centers, and may be 5/16” thick. It has reflective surfaces on the front and back to reflect heat radiation (infrared radiation).

The reflective surface facing inside the house will only be effective if there is space between it and the paneling. You can create space by stapling it to the furring strips draped inward toward the foundation wall. This space will be “dead air space”, which also increases the R-value. The R-value given by one manufacturer is R-3.7, but this depends on how much space is in front and back of it. The effectiveness of dead air space as insulation is greater if the space is larger, so the R-value of the double reflective insulation would be greatest if you drape it inward to the middle of the space.


Wood Siding in Poor Condition

    • If wood siding in poor condition is making your home unattractive, you could lower your utility bills by replacing it and mounting rigid foam insulation sheathing panels behind the new siding. In place of removing the old siding, you may be able to install new siding over the old siding if the new siding is thin. Thin siding could add much insulation value by trapping air behind it if the siding behind it is fairly air-tight.

Installing new siding over old siding would also save the high cost of removal and disposal of the old siding. In some cases, installing siding over old siding makes the home quieter to live in, but not if the windows are single-glazed with no storm windows. Installing new siding will not pay for itself by lowering your utility costs alone, but may pay for itself if it improves the appearance of your home, and may make painting unnecessary. Some communities have guidelines and by-laws limiting the materials that can be used; for example, aluminum siding may not be permitted.

    • If your home has an historic character, there are arguments pro and con for installing siding. If the old siding is removed and replaced, there may be irreversible damage to the historic building materials. It may result in the removal or covering of distinctive trim and other architectural details, or make them appear smaller and recessed into the rest of the building. Also, changing the features of an historic house may have an undesirable impact on the neighboring houses, especially if it is an historic district. An argument in favor of installing siding is that siding that matches the historic material in appearance is often available and could improve the appearance of the house.
    • If you have frame walls with no insulation, it is not very effective to install new siding with rigid foam insulation sheathing behind it because the insulation will not prevent cold air from entering the walls. This has been compared to wearing a sweater at 4” away from your body. You could replace the siding and blow cellulose insulation into the walls after removing the old siding and before installing the new siding. See How to Fill Empty Walls with Loose Fill Cellulose Insulation.
    • Removing and replacing your wood siding allows you to use very good rigid foam insulation sheathing. The best is 1” thick and made of polyisocyanurate, with a reflective surface on one side to reflect heat. One manufacturer claims that it has an R-value of R-6.5, plus the R-value created by the reflective surface. Removing your siding to install a thinner, less expensive insulation sheathing may give you no better insulation than covering over the old siding if the old siding is clapboard. Clapboard has air spaces in front of it when covered by insulation sheathing.
    • If your siding has a significant amount of dry rot, it is better to remove and replace it than to mount new siding over it. It has dry rot if it feels soft and you can stick a nail through it by hand. If you only remove the rotted sections, the wood next to it is likely to have fungus and mold spores. The spores may not die; if their source of moisture is removed they become dormant, and if the wood later becomes moist the spores will cause the wood to rot. Rot can be a health hazard for persons in the home. Fungicides only temporarily kill active fungus.

If your siding has rotted areas and you would rather not remove it, try to find the source of the moisture such as gaps next to windows or a loose fascia board. If you cannot find it and correct it, it would be safer to remove the siding.

    • To help you choose a type of replacement siding and insulation sheathing (or underlayment if you are mounting siding over old siding) and estimate how much you could lower your heating and cooling bills, see Types of Siding Available and also Insulated Siding. .
    • If you are installing new siding over the old, ask your contractor to use 3/8” rigid foam insulated “fanfold” underlayment insulation. Insulation contractors normally use ¼” or 3/8” fanfold rigid foam underlayment insulation, made of extruded polystyrene. These are available with and without a reflective surface, so request insulation with a reflective surface if either the old siding or the new siding has a space next to the insulation. Insulation sheathing and underlayment insulation are explained in Insulated Siding

How Do You Insulate Walls by Doing Repairs to Seal Air Leaks?

If your home was built before the 1960’s, it is important to repair your siding, including brick siding, because the sheathing behind it is normally made of 1”x3″ or 1”x4” boards, and air is leaking through the boards. Plywood sheathing became available In the 1960’s and home builders began using it in all homes. Sheathing built from boards was covered by tar paper or felt paper as a vapor barrier, but air can leak between the seams in the paper.

Repair Brick, Block and Stone Walls

    • If your walls are solid brick, block or stone, or the siding is brick or stone, check for cracks.  You could use binoculars to inspect the upper floors for small cracks. Also, check for cracks in the foundation. Cracks in the walls or the foundation are usually caused by very slight settling of the foundation. They are often above and below windows, where the walls are weakest. Even the smallest cracks should be repaired, because water could enter them and freeze and expand, damaging the mortar and causing bricks to become loose. Cracks can be filled with mortar or with masonry sealant, applied with a caulking gun. Masonry sealant is better because the crack may further expand.
    • There are warning signs that a wall may have small cracks that are hard to see: soft, crumbling mortar; loose bricks; and if the foundation is made of blocks, white stains on the inside of the foundation. Crumbling mortar and loose bricks are the result of water entering cracks and weakening the mortar. To check if a vertical crack is growing, which would be caused by a foundation problem, put a piece of tape over the crack and leave it on for months. If the tape becomes twisted the crack is growing.

If you fill cracks with mortar, a little will smear on the bricks and it is hard to remove. Muriatic acid is effective but very dangerous, and other products are less effective. For this reason, it may be better to hire someone to repair a large crack with mortar.

On walls that are not in direct sunlight, sealant should be applied at least two days after a rain because bricks dry slowly after a rain, especially in colder weather. If your home was built before the 1930’s, do not use the mortar that is sold in home centers and hardware stores to repair a brick or stone wall. This mortar contains Portland cement, which is as hard as concrete. It has been used to build walls since the 1930’s. Before then, masons used a mixture of lime and sand, which absorbed some moisture but allowed moisture to evaporate out. If your walls were built with this type of mortar and you repair them with modern mortar, the moisture will be trapped. When it freezes the bricks could be damaged or the new mortar could fall out.

    • If you have a vine-covered brick wall that is older than the 1930’s, it is possible that the roots of the vines have damaged the softer mortar that was used at that time. Remove some of the vines and inspect the mortar.

Repair Stucco Walls

    • If you have a very old home with stucco siding, the sheathing (the layer of wood behind the siding) may be wide boards instead of plywood or other type of large panels, as is now used. Cracks in the stucco could allow air to leak into your house through the boards. Homes built before the 1960’s, when plywood sheathing became available, had sheathing made from 3” or 4” wide boards.
    1. If you find cracks in the stucco, it would be best to hire a home inspector or home engineer to check if the wall or foundation has a structural fault before repairing the siding.
    2. If there is a structural fault caused the cracks they will probably grow larger.
    3. Repair even the smallest cracks with masonry sealant, because if left un-repaired, water will enter and freeze, breaking off large pieces of stucco.
    4. Scrape out hairline cracks to make them wide enough to caulk.
    • If a small piece of stucco has broken off or if there is a large crack, repair it with stucco repair compound. This is sold pre-mixed, in small containers. With this, you cover the damaged area with a polyester membrane and coat it with compound. After applying the patch, you could cover it with textured paint to disguise it.
    • If a large piece of stucco has fallen off, you can repair it yourself after watching do-it-yourself videos. The hard part is making the patch appear the same as the surrounding area. Here are some tips:
    1. Make test patches on plywood until you can make them perfect.
    2. Stucco is not painted, colored pigment is mixed in to give it color, and the color fades greatly as the stucco dries, so make test patches of several shades and let them dry.
    3. Make the repair when there will be no freezing temperature for a long time. The instructions may require that there be no freezing temperature for six weeks.
Masonry grout bag


Repair Fieldstone Foundation Walls

    • If you have fieldstone foundation walls and air leaks in between the stones, plug the leaks with mortar. If your basement is unfinished, holes in the foundation can be detected on a cold day when the central heating is on. Air will be drawn in forcefully through the leaks due to the “chimney effect”.
    1. Use a masonry grout bag to force in the mortar. This is a canvas bag in the shape of a large funnel. They are sold at building supplies stores.
    2. Fill it 1/3 full of mortar, insert it in the crack and squeeze it to fill the crack.

Repair Unpainted Wood Siding 

    • If you have unpainted wood siding, you could paint it or coat it with a preservative to prevent it from rotting or warping. These types of damage can allow air to leak through on some homes.

• Painting it or coating it with a preservative will help to protect it from rotting and warping. Both of these could allow air to leak through if the sheathing behind the siding is made of boards. As mentioned, if your home was built before the 1960’s, you can assume that the sheathing is made of boards. They are covered by tar paper, but air leaks through that at its seams.

• If your siding is a species of wood that does not require painting, such as cedar, cypress or redwood, or is pressure treated pine, you could protect it by staining it with clear or colored stain or by applying a water repellent product.

• Wood stain is absorbed into the wood, but water repellent products coat and waterproof the more surface. Some products are designed for pressure treated wood. Stains are much expensive and last much longer than water repellent products. Stains have 10, 15, or 25-year warranties. Their durability depends on the quality of the product and on whether the sun shines directly on the wall, and the temperature and dryness of the wall when the stain was applied.

• If you are applying wood stain, ask for advice at a paint store. Instructions may be given on the manufacturer’s website. Before buying any product, read other manufacturers’ websites to compare their products and to help you to choose the best one for your wood and your climate.

Repair Aluminum, Vinyl, and Steel Siding

    • If you have aluminum, vinyl, or steel siding and your home was built before the 1960’s, check for loose or buckled strips. Before sheathing was made of large sheets of plywood, beginning in the 1960’s, it was made from boards nailed diagonally to the frame.  Air that leaks through the siding may leak through the sheathing boards. As mentioned, the boards are covered by felt paper, but there may be gaps where sheets overlap.
    • If your siding has streaking or staining, water may be leaking in and running down the wall from behind the siding. Try to find the source of the water and repair the leak. The wooden sheathing behind it may be badly rotted from the water and need to be replaced. Also, the sheathing may have mold, which could affect the air quality inside your home.
    • If strips of siding buckle when the weather is hot, they were installed incorrectly. The small gaps at the ends of the pieces are not large enough to allow the pieces to expand in hot weather. Do not nail the buckled pieces onto the sheathing. Instead, trim off about ¼” from each end.

Repair Siding That is Not Aluminum, Vinyl, Steel, Masonry, Stucco or Fieldstone

The remaining types of siding are combined here because they can have cracks that can be caulked, and other types of damage that can be repaired.

“Engineered wood” includes various materials that are manufactured by gluing together strands or particles of wood. Fiber cement is a mix of wood pulp and Portland cement. Asbestos siding is a mix of cement and strands of asbestos. Wood lap siding is any wood siding made from horizontally mounted boards.

    • Seal cracks in real wood or engineered wood with clear silicone sealant for outdoor use. Silicone sealant has excellent elasticity. Cracks can take long to thoroughly dry out, especially when the weather is cool, so it may be better to apply the sealant two days after a rain.
    • Seal cracks in asbestos or fiber cement siding with masonry sealant. This adheres well because these materials are made of cement with particles mixed in.

      Ring shank siding nail


    • Nail in any loose nails to prevent the boards from coming loose. Also, check for loose nails in trim boards at windows, ends of walls, etc. If a nail goes in easily, the sheathing may be slightly rotted. Put in two nails near it, driven in at different angles for greater strength. This is called “toe nailing”. Use ring shank siding nails.
    • If a wooden siding board is cracked, put glue or construction adhesive in the crack, close the crack and nail in a nail next to it to hold it closed until the adhesive dries.
    • Repair badly split pieces of shingles or wood siding with polyurethane construction adhesive. This is fills small gaps as does all types of construction adhesive, and is a stronger than most other types. If cracked wood is slightly damp, use a brand of “subfloor and deck construction adhesive”. This sticks to slightly wet wood. If necessary, drill pilot holes and screw the siding to the sheathing while the adhesive dries, and remove the screws later.
    • Repair woodpecker holes. Carve a piece of wood to fit each hole and glue it in with construction adhesive. Construction adhesive fills small gaps, so the plug doesn’t have to fit tightly. If woodpeckers make more holes, they are eating insects
      Asbestos Siding


      in the wood, so spray the siding with insecticide.

    • Fix cracks in asbestos shingles with masonry sealant. These are made of cement filled with particles of asbestos.

Repair Small Rotted Areas In Wood Siding

To repair a small rotted area in wood siding, first find the cause of the rot. Rot is fungus growing in the pores of the wood when the wood is wet, and wood will only rot if it gets wet often. It most often rots because the end of a board is unpainted or not well-caulked, allowing water to be absorbed through the pores of the wood. This may be where two boards meet end-to-end.

The wood is rotted if:

    • Paint is peeling off in one small area
    • The wood is spongy in one area
    • The wood breaks off in chunks rather than splinters

A. Repair Small Rotted Areas Using a Wood Patch

A wood patch is a piece of wood cut to replace the wood in the rotted area.

    1. Do the repair when the weather is warm enough and rain is not forecast, to meet the requirements of the paint.
    2. Cut out the rotted wood and some surrounding wood. The surrounding wood will have fungus in its pores. The easiest way to remove the piece may be to drill a line of 1/8” holes across it.
    3. Cut a piece of wood to fit into the space. A miter saw is the best tool to use. Use a relatively rot-resistant type of wood such as cedar, spruce or hardwood. Don’t use pressure treated wood unless the rotted wood is pressure treated because they can’t be painted with the same paint.
    4. Paint the cut surfaces of the original board with a heavy coat of paint. Brushing it on will not fill the pores, push it into the wood with your finger. Thoroughly paint the cut surfaces of the patch piece. The ends of the patch piece could be dipped into a can of paint to fill the pores with paint. If the original board was painted with oil-base paint, paint the patch piece with oil-base paint, if it was painted with water-base paint use water-base paint. Do this because the final coat of paint will be applied to both the patch piece and the surrounding area, and paint only sticks well to similar paint.
    5. When the paint is very dry, glue in the patch piece with polyurethane construction adhesive. Dry the paint with a hair dryer if necessary. Polyurethane is stronger than most other types of construction adhesive and it fills small gaps, keeping out the water. Use enough to fill the gaps so caulking is not needed. Drill a pilot hole in the patch piece and nail it on with one nail to hold it in place while the adhesive dries.

B. Repair Small Rotted Areas with Wood Filler

    1. Buy wood filler. Exterior epoxy wood filler is the most durable but some brands do not cure below 65º.
    2. Cut out the rotted area. If the rotted area is large, drill many 3/16” holes into the surface you have cut to allow the wood to dry out until the next day (cover it if rain is forecast). Before applying the epoxy, saturate the holes with wood hardener and allow it to dry. This is formulated to strengthen rotted wood. It is sold in paint departments.
    3. Fill the area with wood filler and allow it to dry.
    4. Sand the area.
    5. Prime and paint the area if the temperature and rain forecast meet the requirements of the paint. If the surrounding wood is painted with oil-base paint, use oil-base paint and if it is water-base paint use water-base paint. To know which type it is, check if it rubs off with latex paint remover.

Repair Badly Warped Pieces of Wood Siding

    1. Drill pilot holes so the wood doesn’t split, and nail the siding back into place with ring-shank siding nails.
    2. If the siding cannot be nailed into place because the sheathing behind it is rotted, it would be best to replace that sheathing. If it won’t be replaced, fill the space behind the loose shingle with construction adhesive using a caulking gun, to prevent the siding from warping further. Try to bend it close to the sheathing and keep it there until the adhesive dries by screwing it to the sheathing. Remove the screws after the adhesive dries if they are unattractive. If sheathing is wet, wait for it to dry or use “subfloor and deck construction adhesive”, which adheres to wet wood.

Replace Damaged Boards of Lap Siding

Clapboard siding


Shiplap Siding


Lap siding is any wood siding made from horizontally-mounted boards. Shiplap siding has boards that overlap each other with the top of one board fitting into a notch in the bottom of the board above it. Clapboard siding has boards that overlap each other and are thinner on the top. These may be made from real wood, engineered wood or fiber cement. See Types of Siding Available Shiplap and clapboard are the most common types of lap siding made from wood.

Buy an identical piece of siding. Do not remove the damaged piece until you buy an identical piece because one may not be available. Check at builder supplies stores and lumber yards. Large home centers can deliver siding that is not stocked to their stores. If the piece you need is very old and not available, it may be sold by architectural salvage companies. Remove the damaged piece of siding:

  1. Slip a hacksaw blade under the piece above the damaged piece and cut those nails. Slip the blade under the damaged piece and cut those nails.
  2. Slip a pry bar under the damaged piece, pry it up and put shims behind it to separate it from the piece behind it. Use a small hand saw (e.g., a jab saw) or a jigsaw to cut out the damaged area. A drywall saw can be used if the blade is not dull from cutting drywall. Try not to cut the vapor barrier material behind the siding, but if it is cut, seal it with roofing cement our caulk.
  3. Cut the replacement piece to fit very tightly. To make it fit perfectly, cut it slightly too long and sand it to size with a belt sander or rasp (wood file).
  4. Use a heavy coat of paint to coat the ends of the replacement piece and the cut ends of the original siding, to close the pores and prevent rot.
  5. Slide in the replacement piece. Nail it with ring-shank siding nails, drilling pilot holes so you don’t split the wood. Countersink the nail heads and fill with paintable exterior caulk.
  6. When the paint dries, caulk where the replacement piece meets the old siding. When the caulk is dry, paint the replacement piece.

Replace a Section of a Board of Board-and-Batten Siding

Board and Batten Siding

Board-and-batten siding has wide vertical boards, with thin strips of wood called battens covering the seams where the boards join. It is made in a variety of tree species.

If a vertical board is badly rotted or broken and must be replaced:

  1. Buy a replacement piece of a species of wood similar to what is on your house. If your siding is painted, it is almost certainly pine or fir and you can replace it with premium grade pine. A 10” or 12” wide piece, if you need that, will probably not be available at your local home center in premium grade, but it is sold at lumber yards and building supplies stores. If it is unpainted redwood or cedar, this is only sold at lumber yards and building supplies stores.
  2. Remove the battens over the damaged board using a crowbar.
  3. Cut out the damaged section of board. Cut it with a circular saw, with the blade set ¾” deep to avoid cutting the vapor barrier behind it. If you cut the vapor barrier, repair it with roofing tar or caulk.
  4. If the piece you buy is slightly wider than the piece you removed, cut the piece to a width that allows an 1/8” gap on each side for expansion. It will expand from heat and humidity in the summer. Cut its length to fit in tightly.
  5. Paint the ends of the replacement board heavily to close the pores and prevent rot. Also, paint the original board where it was cut.
  6. Nail the replacement board in place using 2½” ring-shank siding nails. Nail on the battens using the existing nail holes, with longer nails than you removed.

Replace Damaged Asbestos Shingles

It is safe to remove an asbestos shingle if you wear gloves and wash your hands after you remove it. Before removing it, find out what your local ordinance requires for the disposal of a single piece of asbestos shingle.

  1. Buy a matching shingle. Asbestos shingles are no longer sold, but fiber cement shingles that are designed to match asbestos shingles are sold in a large variety of shapes and sizes. They can be ordered at some home centers.
  2. Paint the new shingle and let it dry.
  3. Break the damaged shingle with a hammer and chisel and remove it. This must be done because you cannot bend up the shingle above it to get access to the nails. Be careful not to damage the adjoining shingles. The shingle should be attached by two nails.
  4. Drill two nail holes into the new shingle using a masonry bit. Break away some of the new shingle that would interfere with the old nails and slide in the new shingle. Nail it in using two ring-shank siding nails.

Seal Gaps in Plywood Siding.


Plywood siding is mounted to walls as 4’ by 8’ panels. It is sometimes mounted directly to the wall studs with no sheathing. The panels normally have vertical grooves about every 4” to give the appearance of vertical boards. Check for gaps at the seams where the panels meet, caused by a warped panels. If there is no sheathing, these gaps will allow air to leak directly into the walls. If there are gaps, close them by nailing the edges of the panels to the studs using ring-shank siding nails and caulk the seams with  clear silicone sealant caulk. Check all of the seams for missing or dried-out caulk, and re-caulk them if needed.

DIY Basement Wall Insulation

As explained above, do not insulate the basement walls if you live in a very cold climate. This could cause foundation damage due to “frost heave” if the frost line is as low as the basement floor. If you are unsure of whether your climate is this cold, contact your local HUD /FHA field office.

Before adding insulation to the inside surface of your basement walls, coat the walls with a masonry waterproofer paint such as DRYLOKTM. This product will prevent water from entering the house for up to 10 years, depending on the size of the holes or cracks. In addition to coating the walls you could leave a ½” gap below the insulation and drywall or paneling you install, to prevent any water that leaks in from becoming trapped.

Also before adding insulation, check for signs that water has leaked through. If water is entering your basement, the problem should be repaired before you insulate the walls so the material you mount does not become moldy or in other ways damaged. On a block wall, the water will leave a dark line where it ran to the floor. Also, check for air leaks on a cold day. If your basement walls are block there could be air leaks below ground level because air can flow down through the holes in the blocks. Seal the holes where water or air enters using masonry caulk. If water is leaking through, try to fix the problem in one of these ways:

    • Repair the rain gutters or downspouts.
    • Clean the gutters
    • If water puddles next to the house, add soil near the walls to improve the drainage away from the house.
    • If your yard has a large slope that causes rain water to drain toward your house, hire a contractor to build a “landscape berm”. This is a long mound of earth covered with grass, located to direct drainage away from your house.
    • Waterproof the foundation from the outside, without hiring a contractor. Dig up the ground around the foundation of your home and coat it with an exterior foundation waterproofing product. There are several types: modified asphalts; rubber; and bentonite clay. Some are designed to last the life of the house when applied in new home construction. Some can be applied with a roller. Check with a building supplies store for the product they recommend.
    • Hire a contractor to build a French drain (drain tile) in your basement, or for less cost, build a baseboard system. To build a French drain, the contractor digs a trench in the basement floor along the walls. A large, perforated pipe is laid in the trench, covered with gravel, to drain the water away. A pit is dug in the floor for the water to drain into, and a sump pump in the pit pumps the water out of the house when the pit fills with water. Once completed, the area is cemented over, except for a 2” gap around the edge of the floor. This gap allows water that leaks into the basement to enter the drain. In a baseboard system, hollow baseboards collect water from weep holes tapped in the bottom row of blocks. The water is channeled to a sump pump in a pit, or to a floor drain.

How to Insulate a Basement Wall by Building an Insulated Stud Wall

Your basement walls will have the greatest insulation if you build a conventional wall next to them with fiberglass batt insulation. This is a do-it-yourself project and there are many good do-it-yourself videos on how to do it. The walls should be finished with drywall or paneling, and this could create a “finished” basement if you mount ceiling panels, lay a waterproof carpet or finish the floor in some other way, and install wiring and electrical outlets in the walls.

If you have never built an interior wall, these instructions will not be sufficient. You should watch do-it-yourself videos on building a wall. However,  the videos should include the following:

  1. Using standard construction methods for interior walls, build a wall at 1” from the foundation using 2”x 3” or 2”x 4” boards . The thinnest batt insulation is 3½” thick, but this can be used with 2”x3” boards by peeling away 1” of insulation. The 1” gap behind the wall allows water that leaks in through the foundation wall to fall to the floor. It also allows you to slide plastic sheeting behind the back of the stud wall before you install the insulation.
  2. Buy 3½” thick Kraft-faced fiberglass insulation rolls or batts at a home center or building supplies store.
  3. Buy one roll of polyethylene plastic sheeting at a home center, builder supplies store or paint store. The store should have 20’x 100’ rolls of 6 mil thick polyethylene. Buy ¼” or 5/16” staples to mount the insulation and the plastic sheeting. Buy clear weatherization tape or Tyvek tape to seal the seams in the plastic sheeting. Tyvek tape is available in home centers, where house wrap is sold.
  4. Slide the plastic sheeting behind the stud wall, all across each wall. This is a vapor barrier, it prevents the insulation from absorbing water vapor  that passes through the foundation, and it also makes the basement less humid. Stretch it tightly and staple it to the sides of the wall studs. Seal any seams with tape.
  5. Hire an electrician to install wiring, switches and electrical outlets.
  6. Insert the insulation between the wall studs with the Kraft paper facing the inside of the house. The Kraft paper is a vapor barrier which prevents the insulation from absorbing the water vapor in the house. At the top, extend the insulation back to cover the sill plate (the board resting on the foundation). Leave a gap between the insulation and the floor to prevent the insulation from absorbing water if water enters through the foundation. Staple the Kraft paper tightly to the studs to create air-tight seals.
  7. Finish the walls with drywall or paneling.

• Paneling can be mounted by an experienced do-it-yourselfer who has never done paneling, with a helper, after watching good do-it-yourself videos. First, you should cover the walls with 1/2″ drywall, because modern paneling is thin and not designed to be mounted directly to the wall studs. It would warp badly in the high humidity of a basement. The drywall does not need to be accurately mounted and the seams do not need to be taped and plastered.

• You can finish the walls with drywall only if you are experienced at taping and plastering drywall seams. Do-it-yourself videos cannot substitute for practice here. However, a do-it-yourselfer with no experience at plastering could hang the drywall, and then hire a painter to plaster the seams.

• Whether finishing the walls with paneling over drywall, or with just drywall, use “mold resistant drywall” (green board). This is treated with mold inhibitors. It is available at all home centers and building supplies stores.

• Mount the paneling, drywall and baseboard slightly above the floor to allow for water leakage through the wall. If water becomes trapped behind the wall the frame will rot and become moldy.

How to Insulate Basement Walls of Bare Concrete or Block with Rigid Foam Insulation Covered with Drywall (Wallboard)

If you are an experienced do-it-yourselfer but have never done a project just like this, these instructions will not be sufficient without watching do-it-yourself videos. However,  the videos should include all of the the information below.

    1. Use either 2″x 3″ boards or 1″x 3″ boards (called “furring strips”), nailed every 16″ across each wall. The insulation will be greater using 2″x 3″ boards, but more carpentry work must be done around the doors and windows and the final appearance won’t be as good. If it is very hard to nail into the concrete (if you aren’t very strong), the boards can be spaced 24″ center to center for less nailing. With 2”x 3” boards you can put pieces of 1” thick rigid insulation between the boards and have spaces behind them for dead air insulation. With 1”x 3” boards (furring strips), you can put pieces of ½” rigid insulation between the boards and have ¼” spaces behind them.
    2. If your walls are block, it is good to first paint them with water sealer paint, such as Drylock™. This may prevent water from leaking through, raising the humidity in your home.
    3. Buy rigid foam insulation panels with a reflective surface, of a thickness less than that of the boards. There must be a gap next to the reflective surface for it to add insulation value because it doesn’t reflect heat radiation if it contacts another surface.
    4. The R-values of rigid foam insulation panels are printed on the insulation, but this does not include the insulation value of the reflective surface, which depends on the thickness of the space in front of it; the more space, the better the insulation. As evidence of this, double glazed windows with the widest gap between the two panes of glass have the greatest insulation value. Polyisocyanurate 1” thick rigid foam insulation panels with a reflective surface have an R-value of about R-6, not including the reflective surface.
    5. If you have concrete walls, you could apply polyurethane construction adhesive to the boards before nailing them on you can use one less nail, normally 2 nails per board instead of 3 nails for each board. Brush the concrete clean before nailing on the boards.
    6. Cut the boards. Cut them to a length that allows 2½” above each, to leave space to nail one board across the top. This will prevent air from flowing in or out due to convection, which makes the insulation of the walls much less effective.
    7. Nail on the boards. Make the spacing exact for the insulation to fit tightly between them. This will protect the drywall from vapor from the wall. If the wall is concrete use a power activated nailer, if available. These use gun powder to drive nails. If one is not available, nail the strips with masonry nails using a framing hammer or a small sledge hammer.
    8. If the walls are concrete, the nails should be long enough to penetrate the wall by ½”, whether using masonry nails or a power activated nailer. If the wall is block, drive the nails between the blocks. The length of the nails will depend on how strong the mortar is, so bring 2 sizes.
    9. After the adhesive is dry, which may be the next day, check that the adhesive is holding on the boards. If the walls were slightly wet in places the adhesion will not be strong there, so put in more nails.
    10. If there are windows or a doorway on the wall, you could remove the casing (window frames and door frames), nail on a piece of wood, such as 3/4″x 3/4″,  and re-mount the casing farther from the wall.
    11. Use a 48″ T-square and a utility knife to cut the insulation into strips that will fit tightly between the boards. This will protect the drywall from water vapor. Allow a small space at the bottom of each of piece of insulation because they will be mounted slightly above the ground.
    12. Buy drywall and baseboard. It must be mold resistant drywall (“green board”).
    13. Hang the drywall. Leave a small gap at the bottom for water to drain through if it leaks through the walls. Tape and plaster the seams.
    14. Either tape and plaster the seams or mount paneling. Plastering must be done by an experienced person, but an experienced do-it-yourselfer can mount paneling with the help of a do-it-yourself videos. Paneling should not be mounted without drywall because it would be damaged by the high humidity in the basement.
    15. Nail on the baseboard, leaving a very small gap at the bottom for water to drain through.  Caulk all along the top (you may prefer to caulk it after painting the walls).

Insulate Bare Concrete or Block Basement Walls with Rigid Foam Insulation Boards Not Covered by Drywall (Wallboard)

  1. To insulate your basement walls and not cover them with drywall, you could nail furring strips to the walls and nail 4’x 8′ sheets of rigid foam insulation to them. Insulation boards that do not have a reflective surface can be painted, and you can use thick boards for excellent insulation if you choose. A reflective surface increases the insulation value of a panel by reflecting heat radiation (infrared radiation) and for less cost than using a very thick panel without it, and painting it would make the surface ineffective.
  2. Furring strips are used because each can be nailed on with only 2 nails,  and the panels are permanently mounted to them with roofing nails. Also, the furring strips are ¾” thick, which creates a ¾” space. This is “dead air insulation”, which is very effective.
  3. WARNING – Most brands of rigid foam insulation cannot be used because they emit noxious fumes in a fire. These have warnings on their labels such as “This product should be separated from the building interior by a thermal barrier, usually ½” gypsum board” (gypsum board is normally called drywall or wallboard.
  4. If your walls are block, it is good to first paint them with water sealer paint, such as Drylock™. This may prevent water from leaking through, raising the humidity in your home.
  5. Buy enough 1″x 3″ furring strips to mount one vertically every 24″ and one horizontally across the top, along all of the walls. Furring strips are rough, inexpensive boards used only for this purpose.
  6. Cut the furring strips 2½” shorter than the height of the walls. This will leave room to nail one strip across the top (they are 2½” wide).
  7. Nail on the furring strips every 24″. Mount them very accurately so that the edges of the insulation panels will extend to their exact centers so the panels can be nailed to them. If the walls are concrete, you could use a power activated nailer, if available, with 2″ nails. These use gun powder to drive nails. If one is not available, nail the strips with masonry nails using a framing hammer or a small sledge hammer, with 2″ masonry nails. If your foundation is block, nail between the blocks. The length of the nails will depend on how strong the mortar is, so bring at least 2 sizes of nails.
  8. Nail furring strips across the top. This will prevent air from flowing in or out due to convection, which makes the insulation of the walls much less effective.
  9. Mount the first row of 4’x8’ insulation panels horizontally along the walls, over  the furring strips. Leave a ½” gap at the bottom for water to drain out if it leaks through the wall. Cut the insulation using a T-square and utility knife. If they have a reflective surface it must face inside the house. Nail on the panels with roofing nails.
  10. Cut and mount the second row of panels. Seal the seams with TyvekTM tape to block moisture from entering the house. This is available in home centers, where house wrap is sold.
  11. Paint the panels if they not foil faced.

How to Fill Empty Walls with Loose Fill Cellulose Insulation

First, decide whether to fill the walls from the inside or the outside of the house. If you have siding in horizontal strips (lap siding), it may be easier to fill the walls from the outside, by removing one or two strips on each wall. Blowing in the insulation from the outside would then be a do-it-yourself project. Filling the walls from the inside would require that you hire someone (normally a painter) to repair the many 2” or 3” holes in the wall, and you would also need to re-paint the walls. If you have brick or stucco walls you must blow in the insulation from the inside.

If you are an experienced do-it-yourselfer and you attempt to fill the walls with insulation, you should first watch a few good do-it-yourself videos. This section will add to what the videos show.

Fill the Walls from Inside the House

  1. In some very old homes, loose fill insulation can be poured into the walls from the attic because the spaces between the wall studs are open at the top. If your home is very old, check if your walls are open at the top.
  2. Some old homes have fiberglass insulation that is only about 1” thick. The walls can be filled using an insulation blower, but it is more difficult than if the walls were empty, and may not be worth the time and expense if your climate is not cold. If you rent a blower from an insulation company, they may be able to advise you on how to do this.
  3. If your home has very old wiring, hire a qualified electrician to inspect the wiring in the exterior walls before installing insulation. An electrician can inspect it by looking into the electrical boxes at the switches and outlets on the exterior walls. In many old homes, some circuits have the original wiring and other circuits have more modern wiring, so if you see modern wiring in the basement, you can’t assume that all of the wiring is modern. You can check if some of your home’s circuits have very old wiring by checking the cables as they enter the main electric panel. If they all are covered with plastic insulation (Romex wiring), you have no very old cables.
  4. If any walls show evidence of water leaks, have the leaks repaired before installing insulation. New insulation could absorb water and remain wet for a long time, causing damage to the walls.
  5. Rent an insulation blower and buy the insulation. Ask the salesperson for advice on how to use the blower. Buy plastic plugs to repair the holes in the sheathing (the panels or boards which the siding is nailed to) if you will blow in the insulation from the outside. These are not sold everywhere that blowers are rented. Insulation blowers can be rented at home centers, rental centers, builder supplies stores, and some insulation supply companies, but only insulation supply companies would probably offer you good advice on using them. Also, you may need to go there to buy plastic plugs. See, “Fill the Walls from the Outside of the House”, directly below. Ask to borrow a 12-amp extension cord if you don’t own one.
  6. Hoses 50’ and 75’ long should be available. Use a 50’ hose if this is long enough because insulation will flow through it more easily.

Fill the Walls from Outside the House

  1. Remove one row of siding at the top of each floor. If you have aluminum siding, you must watch a video. After removing a piece of aluminum siding, cut the house wrap or other vapor barrier where you will drill holes, and peel it down to be stapled up later. If you have wood or fiber cement lap siding, first cut the caulk that bonds the siding board at its ends. Then, pry up the piece ¼” to ½” with a stiff, wide-blade putty knife and tap it back into place. The head of a nail should then stick out slightly and the nail can be pulled out. There should be one nail every 16”. Cut the house wrap or other vapor barrier where you will drill holes, and peel it down to be stapled up later. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  2. After removing the row of siding, drill holes for the hose, into the sheathing at 16” intervals, midway between each pair of wall studs. The nails in the sheathing will show the stud locations. At each hole, drop a weight on a string to check if the cavity extends to the bottom of the floor. There may be a board about half-way up the wall, which is a fire stop. If so, remove a row of siding directly below it for the hose.nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  3. To blow in the insulation, carefully read the instructions given with the blower. Mount the ladder firmly and be careful not to trip on the hose as you climb the ladder. Insert the blower hose to the bottom of the cavity and then turn on the blower. Slowly pull out the hose while filling the cavity with insulation. When the space is filled, insulation will blow out from the hole. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  4. Plug the hole in the sheathing with plastic plugs if you have them. They are sold by some insulation companies. If not available, cut a ¼” plywood panel into 6”x6” pieces and glue a piece over each hole with construction adhesive. Use an adhesive labeled to be for “indoor/outdoor use” and with a “high tack”. An adhesive’s tack is a measure of how well the objects stick together when first joined. If the tack is high and you use ¼” plywood the panel will stick immediately so you won’t need to nail it. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  5. Put the building paper back in place and staple it or nail it with ¾” roofing nails, and then tape it where it was cut using Tyvek tape. Replace the siding. If the siding is wood or fiber cement lap siding, nail it on using the original nail holes to prevent water from entering the holes. Use nails that are ½” longer than the original nails. If you use new nails, use ring-shank siding nails or spiral galvanized nails. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  6. If the siding is wood or fiber cement lap siding, carefully caulk  the gaps at the ends of the piece of siding with exterior caulk or sealant.

Fill the Walls from Inside the House

  1. With the blower outside the house, extend the hose into the house through a window. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  2. Locate the wall studs. Use a stud finder or knock on the walls to find the approximate location of each wall stud. The wall will feel solid at every wall stud, which will be spaced 16” apart. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn

    Hole saw bit


  3. Use a hole saw bit to drill holes for the hose between every two wall studs at the top of the wall. Leave a space of several inches above each hole to allow for plaster repair. WARNING – Drill in only to the depth of the wall material  (normally ½”) to avoid cutting a cable. Wrap masking tape around the drill bit to mark how deep to drill each hole. Very old homes had plaster walls which were made of plaster on wood lath strips, and were thicker than ½”. Always check by drilling in exactly ½” because the original wall may have been replaced with a drywall in one area. Drop a  weight on a string into each cavity to check if it extends to the bottom of the floor. Do this for every hole. There may be a board about half-way up  the wall, which is a fire stop. If so, drill a row of holes directly below it. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  4. To blow in the insulation, carefully read the instructions given with the blower. Insert the blower hose to the bottom of the cavity and then turn on the blower. Slowly pull out the hose while filling the cavity with insulation. When the space is filled, insulation will blow out from the hole. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  5. Hire an experienced person to repair the holes. Experienced house painters are normally qualified.

Types of Siding Available

These types of siding are currently sold; older homes have many other types of siding.

Engineered Wood Siding

Engineered wood siding, which is made from “engineered wood”, also called composite siding, is manufactured by binding particles or fibers of wood with glue. The materials used are treated with chemicals that make them rot-resistant, but this type of siding does not always last as long as real wood. The maximum warranty available may be 30 years, and some warranties are only 20 years. Their life is hard to predict, especially for brands that have not been on the market long. They require similar maintenance to wood siding, to be painted every 5-10 years.

It has advantages over wood siding:

    • Less costly
    • Pre-primed so it can be installed without painting
    • Available in longer pieces (16 ft.), so there will be fewer seams

Its main disadvantage over wood siding is that it will eventually need to be replaced.

Fiber Cement Siding

Fiber cement siding is a mix of wood pulp and Portland cement. It is fire-proof, rot-proof, and termite-proof. It is used on many new homes. It is available in pieces resembling the most popular styles of wood siding; clapboard, shiplap, shingles, etc. The pieces are nailed on like wood siding and can be cut like wood. It looks just like wood but costs much less. Installing it is not a do-it-yourself project.

It is not available as insulated siding with foam fused to the back, but it can be mounted  over insulation sheathing to obtain a high R-value.

Fiber cement siding that absorbed water


Fiber cement siding has several problems:

    • It is the most difficult type of siding to install properly and many installers are poorly-trained and install it poorly.
    • Its worst problem is that it can absorb water and swell up if it is in a very wet location on the wall, such as where gutters overflow. It is made with wood pulp, which can expand when wet.
    • In areas on the walls where the siding gets very wet, if fiber cement siding absorbs even a small amount of water, the paint can peel.

Board and Batten Siding

Board-and Batten Siding


Board and batten siding is made from wide vertical boards of real wood, with thin strips of wood, called “battens” covering the seams where the boards join. It is available in several species of wood, including cedar, redwood and pine, but some species are only available in certain regions on the country. This type of siding can be very attractive.


Shiplap and Clapboard Siding



    • Shiplap siding is made of horizontally-mounted boards, which overlap each other with the top of one board fitting into a notch (rabbet) in the bottom of the board above it. The boards can be made real wood or engineered wood or fiber cement.
    • Clapboard siding is made of horizontally-mounted boards that are thinner on the top. Each board overlaps the board below it. It has a higher R-value than shiplap siding because there is a space behind each board which is dead air insulation.
    • Shiplap and clapboard siding  are called “lap siding”. There are other, uncommon types of lap siding. The most common types of wood used for shiplap and clapboard siding are pine, white fir, cedar and redwood. Pine and white fir are not rot-resistant so they must be painted or stained regularly. Cedar and redwood have a natural resistance to decay, but they should be coated periodically with a wood preservative or wood stain.  Applying wood preservative or wood stain is much easier than painting, and is a do-it-yourself project.
    • Lap siding can be installed by experienced do-it-yourselfers, but it takes much more time than installing vinyl or aluminum siding.

Plywood Siding

Plywood siding


Wall Covered by Plywood Siding


Plywood siding is a low-cost alternative to other types of siding, and is also the quickest and easiest to install. It has acceptable durability in dry climates. It is installed as 4’ x 8’ panels with grooves to give the appearance of vertical boards. It can last up to 30 years if properly maintained, but it often rots at the bottom because the homeowners didn’t adequately paint the bottom edge, allowing water to “wick” in.

Vinyl Siding

    • Vinyl siding is the most popular type of siding for covering existing siding. It competes mainly with aluminum siding. They are both relatively inexpensive, easy to install and require little maintenance. Vinyl requires less maintenance than aluminum, but it should probably be washed periodically. It becomes brittle in cold weather, so it can be damaged more easily when the weather is cold. For this reason it isn’t normally used where the climate is very cold. It is probably the easiest siding for do-it-yourselfers to install.
    • Vinyl siding doesn’t have some of the problems associated with aluminum siding: the paint scratching off, denting, and being noisy when wind blows. It is growing in popularity, partly because it has attractive styles which imitate the look of wood siding. It is made of PVC, with the coloring in it. As a result, scratches are not noticeable and it doesn’t need painting. It has the problem that it can break, but the heavier brands are fairly strong, they can withstand stones thrown by lawnmowers.
    • Its problems are that it has a small tendency to crack and split, and it can look faded and dingy after not too many years. Some homeowners paint it, but this is not recommended. Manufacturers have made some improvements on these problems.
    • There is a common belief that vinyl siding insulates better than aluminum siding because aluminum conducts heat faster. In fact, it insulates only very slightly better than aluminum because most of the resistance to heat flowing through any type of siding is created at the siding’s inner and outer surfaces. The outer surface resists solar radiation (UV radiation) and the inner surface resists heat radiation (infrared radiation). Also, the air behind the insulation is “dead air insulation” but is much less effective because hot or cold air behind it flows out in a convection cycle.
    • Insulated vinyl siding is bonded with StyrofoamTM   or another brand of foam. The brands with thick foam insulate well.  Also, thick foam insulation makes it much stronger against impacts because the insulation fills space behind it. This extra strength also prevents it from becoming slightly “wavy”, which can happen to vinyl siding. Some of its manufacturers claim that it allows vapor to pass through it from the inside better than other insulation products. Allowing vapor to escape prevents mold from growing in the walls. Ask the contractor who would install it if their product is “breathable”.
Dutch lap insulated vinyl siding


Clapboard insulated vinyl siding


Aluminum Siding

4" aluminum siding with wood grain finish


Aluminum siding is the second most popular type of siding for covering existing siding. It has these advantages over the other types of siding:

    • Easiest to install, so there is less risk of poor installation
    • Most durable.
    • Can be used in very cold climates, where vinyl siding is prone to crack
    • Unlike vinyl siding, it is normally fade resistant, but some painted finishes can fade or allow chalk to run onto brick walls below it.
    • Like vinyl and steel siding but not the other types, it is available with thick foam insulation bonded to the back of it.
    • Available in a wide variety of colors and finishes, including wood grain finish.
    • Has several disadvantages, which together have made it less popular than vinyl siding:
    • Paint can scratch off, but newer, more expensive vinyl-coated finishes are more scratch-resistant.
    • Prone to denting
    • Can be noisy when the wind blows
    • Lacks the ability for detailed trim work.
    • Prevents a Wi-Fi signal from passing through, so members of the household cannot use laptop computer or other portable device on the porch or patio. It causes no problem with the Wi-Fi signal inside the house.

Insulated aluminum siding is bonded with StyrofoamTM   or another brand of foam. This increases the R-value significantly if the foam is thick, but some brands have a thin sheet of foam.

Steel Siding

Steel siding has several advantages over vinyl and aluminum siding:

    • May have the best long-term value
    • Not prone to denting
    • Superior protection against high winds and hail

It has many disadvantages:

    • Not available in as many styles and colors as vinyl and aluminum
    • When it gets scratched it should paint the scratch immediately to prevent rust.
    • It is hard to handle and cut, so installing it is not a do-it-yourself project. To install it you must find a contractor who is experienced with steel siding, not aluminum siding.
    • Insulated steel siding may not be available, but you can install steel siding over insulation sheathing. See below Insulation Sheathing: Panels and Fanfold Underlayment
    • Lacks the ability for detailed trim work.

Insulated Siding 

If siding of any type is mounted over insulation sheathing, it can be called “insulated siding”. The insulation sheathing is normally a foam sheet that covers the walls under the siding. Vinyl siding with rigid foam, such as Styrofoam™ bonded to the back of it is also called insulated siding.

    • Insulation sheathing insulates by resisting heat flowing through it. Some insulation sheathing has a reflective surface, which insulates by reflecting heat radiation (infrared radiation). This only adds insulation value if there is a space next to the reflective surface.
    • If your home is older than 1960’s, when plywood was first used as sheathing, your sheathing is wide boards nailed diagonally onto the wall studs.  The sheathing was covered with tar paper or felt paper as a vapor barrier, and the siding was mounted directly to it.  The sheets of vapor barrier were not taped at the seams, they simply overlapped, so air leaks through into the walls. If your home is older than the 1960’s and you install siding that is not designed to be air-tight, and the installers do not replace the old tar paper or felt paper, air will leak through into your walls. Insulation sheathing will prevent this.
Fanfold Underlayment


    • If you mount siding over existing siding, first cover the existing siding with thin insulation sheathing called “fanfold underlayment”. This is sold in 4 ft. by 50 ft. pieces that fold up like a fan. It is the only type of thin insulation sheathing.  You only need to apply tape to the top and bottom seams, not the panels’ sides. Seal the seams above and below each sheet with Tyvek™ tape. Fanfold underlayment is available in thicknesses of ¼” and 3/8”, with and without  a reflective surface on one side.
    • Insulation sheathing can be made from several types of rigid foam, and of several thicknesses. Each type of rigid foam has a different R-value in sheathing of the same thickness. The R-values are printed on the panels. The material is usually not printed on the panel. The panels made of blue, green or pink rigid foam are made of extruded expanded polystyrene, such as Styrofoam ™. It has a relatively low R-value and is less expensive. Its R-value is R-5 for a 1”thick panel and R-3 for a ½” panel. Polyisocyanurate has a higher R-value and is more expensive. A 1”thick panel has an R-value in the range of R-6 to R-7. Panels made of polyisocyanurate have one reflective surface on each panel, so add the R-values created by the reflective surfaces, which is very roughly R-2. The insulation value added by a reflective surface will be greater in very hot or very cold climates, and greater if the space next to it is greater.
    • Rigid foam insulation panels ranging from ½” to 1” thick can be used as insulation sheathing if you are replacing the siding, but these panels are too thick to fit between old siding and new siding. Fanfold underlayment must be used.
    • The R-values printed on the insulation sheathing can only be used to compare the panels because the increase in the R-value of your walls which they would add depends on several factors. The panels will increase the R-value of your walls by much less than the value printed on them, and it is hard to estimate what it will be. If your siding is not designed to trap air behind it, insulation sheathing will be much more effective because it will trap air to create dead air insulation.
    • Panels with a foil-faced reflective surface are impermeable, that is, vapor cannot pass through them. Panels with no facing of any material are semi-permeable. Panels labeled as “vapor retarder” have a facing that is not a foil-faced reflective surface. They are less permeable than panels with no facing. If you want insulation sheathing that has a relatively high R-value and is not impermeable, i.e., it allows no vapor to pass through, you may have to buy it at an insulation supply company. Your local home center will probably only carry one type of high R-value insulation sheathing and it has a reflective surface.
    • To create the highest R-value, tape the seams. Some panels have “shiplap edges” which create tighter seals. If you have hired a contractor to mount the insulation sheathing, check that he is taping the seams and fitting the edges tightly together. If you will install it yourself, obtain instructions from the manufacturer. You should also check your local building and fire codes.

How Much Could Insulation Sheathing Lower Your Heating and Cooling Costs?

If you mount insulation sheathing when replacing your siding, there are situations where it would probably be a good investment. If you mount the insulation sheathing yourself and save the cost of labor, it is likely to be a good investment. If it is very cold where you live, and especially cold and windy, insulation sheathing is likely to be a good investment.

A DOE study done in 2004 at the Oak Ridge National Laboratory titled, “Retrofit Best Practices Guide: How to Save Energy When You Fix up the Outside of Your Not-So-New House” estimated a homeowner’s potential savings in heating and cooling costs if they remove siding that has no insulation sheathing and replace it using insulation sheathing. The study compares two types of rigid foam, at different thicknesses, with and without foil facing. The results can be better understood by knowing that polystyrene is R-5 per inch of thickness and polyurethane is about R-6.5 per inch of thickness. The study estimated the range of potential savings in ten cities. The results are given below for two of those cities, Chicago and Atlanta. Single-story homes are more likely to be near the bottom of the ranges.

Potential Annual Heating and Cooling Energy Savings for Different Wall Retrofit Options in Chicago

Is Vinyl Siding Bonded to Rigid Foam a Good Investment?

Vinyl siding bonded to rigid foam costs about 50 percent more than the same siding  without the rigid foam, but the cost of labor may be about the same. Basically, it is probably cost effective wall insulation in climates with extreme heat or cold, where  the payback period could be as short as five years.

This web page, “DIY wall insulation” shows that even if you have no experience, but you are handy, you can lower your heating and cooling bills by doing many large and small things.